Plain bearing bushes for use in connection with the frictional bearing of rotating components are known. For example, German Offenlegungsschrift No. DE 29 13 708 A1 discloses a bearing bush with lubricant pockets made in the supporting running surface. The bearing bush has an essentially hollow cylindrical shape, with the material which is displaced when the lubricating pockets are shaped forming cams projecting on the outside jacket of the bearing bush.
A similar approach is known from German Offenlegungsschrift No. DE 33 26 316 A1. This document discloses a sintered metal bearing bush with lubricant pockets, wherein recesses are provided for holding lubricants on the running surface which lies inside.
Diverse similar approaches are also known, reference being made by way of example to German Offenlegungsschrift No. DE 2 234 428 A1, German Offenlegungsschrift No. DE 1 910 692 A1 and U.S. Pat. No. 824,628.
In the production of these plain bearing bushes, it is desirable to produce a bearing bush characterized by a long service life, with the production of the bearing bush being as relatively simple and economical as possible.
In the studies of rolled cylindrical bushes of bronze, as per DIN 1949 (ISO 3547), in the version with rhombic lubrication pockets, it has been found that after initial greasing under a load of roughly 40 N/mm2 with oscillating motion and a unilateral load direction, the end of the service life is reached early if there is no regreasing after roughly 24 hours of testing.
Under otherwise identical conditions, if rolled bronze bushes were used which are provided with a blanket pattern of through holes instead of rhombic pockets, a regreasing period of roughly 48 hours was sufficient to prevent a premature end of the service life.
If this test is carried out with identically perforated bushes which consist of steel and in addition to nitriding have manganese-phosphatizing of the surface, test times of more than 1300 hours without further regreasing were reached. The repetition of this test with the described steel bushes and a pressure of roughly 60 N/mm2 showed a comparatively disappointing result with only roughly more than 5000 m of sliding path until failure.
Other tests with composite bushes using polyacetal (material group P2 as per DIN 1494) disclosed that these bushes attain slide paths of more than 6000 m until failure without any initial lubrication even when running dry at a pressure of 100 N/mm2.